Negotiators for the U.S. government and victims of the devastating 2010 BP oil spill in the Gulf of Mexico are making a last-minute effort to resolve the massive damage case against the British oil giant.

A trial about who is responsible - and to what degree - for the worst offshore oil spill in U.S. history is scheduled to start Monday in New Orleans, Louisiana. It is near where a BP oil rig exploded nearly two years ago, killing 11 workers and spewing almost five million barrels of oil into the waters off the southern U.S. coast over an 87-day period.

BP and several companies that worked with it or shared ownership of the drilling operation could be liable for billions of dollars in damages. Already, more than 72 million pages of evidence have been collected in 536 lawsuits stemming from the disaster. Federal judge Carl Barbier is set to hear the collected cases in a trial could last into 2013.

The negotiators, however, are seeking to reach an agreement on the damages and end the need for a trial. The main defendants are BP, which had a 65 percent stake in the well; the Swiss company Transocean, which owned the rig, and U.S.-based Halliburton, which provided cement services for the drilling operation. They have sued each other as well.

BP has accepted responsibility for the disaster, and says its legal and cleanup costs could total $43 billion. But the company is also looking to shift some of the blame to other companies and has already reached settlements with some of them that played lesser roles in the explosion.

However, an overall settlement of the damages has proved elusive, in part because of the complexity in calculating the vast damages and assigning the appropriate share of blame. The U.S. government is looking to collect massive damages for violation of the country's environmental laws.

Thousands of individuals who live along the Gulf of Mexico shoreline and businesses that operate there are also seeking payouts. They say the seafood and tourist industries were severely damaged as the seeping oil spread across the waters in the three months before the well was capped.

Former BP chief executive Tony Hayward apologized for the accident in 2010, but angered many residents near the oil rig when he seemed just as concerned about the amount of time he was spending two summers ago on the clean-up effort.

"We're sorry for the massive disruption it has caused to their lives," he said. "There's no one who wants this thing more over than I do. You know, I'd like my life back. So, there is no one who wants this thing done more than I do and we are doing everything we can.''

Whether the case is settled this weekend, or goes to trial, the expected damages are all but guaranteed to make it the most expensive environmental disaster in U.S. history, far surpassing the $1 billion Exxon paid for its Exxon Valdez oil tanker spill in 1989.